Assembly requires the placement of one part upon another. In the past, this has been manually accomplished, particularly in those cases where small parts of different sizes and shapes were to be placed upon different locations on a larger support. Automated assembly technology originated in the placement of the same size part in the same location, and then proceeded to placement of the same size part in different locations. This type of assembly is particularly practiced on a printed wiring board where complex wiring interconnections can be provided by etched conductive leads on a dielectric board. Components are placed in position on the printed wiring board and are connected to the leads thereon. In handling such components, most of the prior art developments were in the category of dedicated tooling, where the tooling is designed to perform one function or handle components of a single size. Such dedicated tooling is expensive, if it can only be used in such a limited manner Technical development has resulted in finger systems and other part-handling devices which can pick-and-place devices of various sizes and styles. One problem associated with all pick-and-place automatic equipment is that the program may have an error therein or there may be an unexpected obstacle on the path of the pickup device. When the pickup fingers run into an obstacle, the fingers may be damaged and the obstacle may be damaged. In either case, there will be a loss in productivity due to machine down time and due to equipment and/or part damage. There is a need to be able to terminate the movement of a pick-and-place machine when an obstacle is encountered.